Section III Enhanced/Improved Oil Recovery (EOR/IOR) Characterization
The Nash Draw pool in Eddy County, New Mexico, is a field demonstration site in the Department of Energy Class III (Slope Basin Clastic Reservoirs) program. Production is from the basal Brushy Canyon zones of the Permian (Guadalupian) Delaware Mountain Group. The basic problem at the Nash Draw pool is the low recovery typically observed in similar Delaware fields. By comparing production performance for a control area using standard infill drilling techniques to a pilot area developed using advanced reservoir characterization methods, the goal of the project is to demonstrate that advanced technology can significantly improve oil recovery.
During the first two years of the project, six new producing wells were drilled for data acquisition wells. Vertical seismic profiles and a 3-D seismic survey were acquired to assist in interwell correlations and facies prediction.
Restricted surface access at the Nash Draw pool, caused by the proximity of underground potash mining and surface playa lakes, limits field develop-ment with conventional drilling. Combinations of vertical and horizontal wells combined with selective zone completions are being evaluated to improve production performance.
Based on the production response of similar Delaware fields, pressure maintenance is a likely requirement at the Nash Draw pool. A detailed reservoir model of the pilot area was developed, and enhanced recovery options, including waterflooding, lean gas, and carbon dioxide injection, were considered.
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Reservoir Characterization—Recent Advances
Optimum reservoir recovery and profitability result from guidance by an effective reservoir management plan. Success in developing the most appropriate reservoir management plan requires knowledge and consideration of (1) the reservoir system, including rocks, fluids, and rock-fluid interactions, as well as wellbores and associated equipment and surface facilities; (2) the technologies available to describe, analyze, and exploit the reservoir; and (3) the business environment under which the plan will be developed and implemented. Reservoir management plans de-optimize with time as technology and the business environment change or as new reservoir information becomes available. Reservoir characterization is the process of creating an interdisciplinary high-resolution geoscience model that incorporates, integrates, and reconciles various types of geological and engineering information from pore to basin scale. The reservoir data are then conceptually and quantitatively modeled and compared to the historical production data and fluid flow distribution patterns within and beyond the limits of the reservoir to match well production histories and predict their behavior. The goals of reservoir characterization are to simultaneously (1) maintain high displacement efficiency, (2) optimize high sweep efficiency, (3) provide reliable reservoir performance predictions, and (4) reduce risk and maximize profits. Notice that in addition to the technical concepts that we normally associate with "characterization," maximizing profits is an essential element of this process. Papers from the Fourth International Reservoir Characterization Technical Conference (1997), sponsored by the U.S. Department of Energy, this publication is a unique compilation of 27 papers covering every aspect of reservoir characterization and has been a popular AAPG publication since that time. Using an interdisciplinary approach, the papers address qualitative information as well as integrated quantified data and culminate in a fully integrated study.